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/*
* June 27, 2001 Manuel Novoa III
*
* This is a heavily modified version of gcc's output for the _syscall5 macro.
* The idea (originally from dietlibc) is that all syscall functions simply set
* the syscall number as the first argument, then set the syscall arguments as
* the next up-to-five arguments, and then jump here. All the common work is
* done by syscall(), saving a fair amount of generated code when a number of
* syscalls are used. The (potential) cost is some unnecessary pushes, pops,
* and movs but the execution time penalty should be relatively small compared
* to the cost of the syscall itself.
*
* July 24, 2002
*
* Modified by Erik Andersen to take all function parameters from off the stack
* like a proper function and eliminates the old 255 syscall number limit. So
* now we can just call this as a function as syscall() per the function
* prototype in unistd.h, so to call _exit(42) you can just call.
* syscall(__NR_exit, 42);
* and things will just work.
*/
.text
.global syscall
.type syscall,%function
.align 4
syscall:
pushl %ebp
pushl %edi
pushl %esi
pushl %ebx
movl 44(%esp),%ebp /* Load the 6 syscall argument registers */
movl 40(%esp),%edi
movl 36(%esp),%esi
movl 32(%esp),%edx
movl 28(%esp),%ecx
movl 24(%esp),%ebx
movl 20(%esp),%eax /* Load syscall number into %eax. */
int $0x80
popl %ebx
popl %esi
popl %edi
popl %ebp
cmpl $-4095,%eax
jae __error
ret /* Return to caller. */
__error:
jmp __syscall_error
.size syscall,.-syscall
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